Current mobile communication is more and more tending to provide multimedia service with high rate transmission to users. A system architecture of System Architecture Evolution (SAE) includes elements to provide mobility context, session context and security information of the UE.
The 3rd Generation Partnership Project (3GPP) has proposed requirements of small cell enhancement in release 12 (Rel-12). Target scenarios of the small cell enhancement include scenarios with macro cell coverage and without macro cell coverage, indoor and outdoor, ideal and non-ideal backhaul enhancement.